Bi-directional stent delivery system

ABSTRACT

A bi-directional stent delivery system includes an inner elongate shaft, a radially expandable prosthesis disposed over the inner elongate shaft, an outer elongate shaft, and a shuttle sheath disposed over the radially expandable prosthesis. The distal portion of the inner shaft is releasably coupled to the distal portion of the shuttle sheath, and the distal portion of the outer shaft is releasably coupled the proximal portion of the shuttle sheath. Distal advancement of the inner shaft advances the shuttle sheath distally when the outer shaft is uncoupled from the shuttle sheath, thereby allowing the prosthesis to radially expand from a proximal end to a distal end. Proximal retraction of the outer shaft retracts the shuttle sheath proximally when the inner shaft is uncoupled from the shuttle sheath, thereby allowing the prosthesis to radially expand from a distal end to a proximal end thereof.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a Division of application Ser. No. 12/911,604, filed Oct. 25,2010, now U.S. Pat. No. 8,864,811, which claims the benefit of priorityof U.S. Provisional Patent Application No. 61/352,408, filed Jun. 8,2010. The disclosures of the prior applications are hereby incorporatedby reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical devices, and moreparticularly to endoluminal delivery systems for prostheses such asstents, or other implantable structures. The delivery systems may beused for placement of a stent in the arterial system, the venous system,or any other portion of the body. The use of stents and otherimplantable medical devices such as grafts, stent-grafts, filters,shunts, valves, etc., are referred to herein as prostheses. Prosthesesmay be used to deliver drugs to tissue, support tissue, or maintainpatency of bodily lumens, as well as performing other functions, andhave been widely reported in the scientific and patent literature.

Stents are typically delivered via a catheter in an unexpandedconfiguration to a desired location in the body. The combined stent andcatheter is typically referred to as the stent delivery system. Once atthe desired location, the stent is expanded and implanted into the bodylumen. Examples of locations in the body include, but are not limitedto, arteries (e.g. aorta, coronary, carotid, cranial, iliac, femoral,etc.), veins (e.g. vena cava, jugular, iliac, femoral, hepatic,subclavian, brachiocephalic, azygous, cranial, etc.), as well as otherlocations including the esophagus, biliary duct, trachea, bronchials,duodenum, colon, and ureter.

Typically, a stent will have an unexpanded configuration with reduceddiameter for placement and an expanded configuration with expandeddiameter after placement in the vessel, duct, or tract. Some stents areself-expanding, and some stents are mechanically expanded with a radialoutward force applied from within the stent (e.g. with a balloon). Somestents have one or more characteristics common to both self-expandingand mechanically expandable stents.

Self-expanding stents are made from a material that is resilientlybiased to return to a pre-set shape. These materials may includesuperelastic and shape memory materials that can expand to an implantedconfiguration upon delivery or through a change in temperature.Self-expanding stents are constructed from a wide variety of materialsincluding nitinol (a nickel titanium alloy), spring steel, shape-memorypolymers, etc.

In many stent delivery systems, particularly those used to deliver aself-expanding stent, the stent is typically retained on the catheter inits unexpanded form with a constraining member or other retention devicesuch as a sheath or outer shaft. The stent may be deployed by retractingthe outer shaft from over the stent. To prevent the stent from beingdrawn longitudinally with the retracting shaft, many delivery systemsprovide the catheter shaft with a pusher, bumper, hub, holder or otherstopping element.

Precise delivery of stents can be challenging. In the case of balloonexpandable stents, the stent may foreshorten as the stent radiallyexpands, therefore, the change in length must be taken into account whendeploying the stent at the treatment site. In the case of self-expandingstents, due to the elastic nature of the stents, they may “jump” awayfrom the delivery catheter during deployment. For this reason, it wouldbe desirable to provide improved stent delivery systems that canaccurately deliver a prosthesis such as a stent to a desired treatmentsite. Additionally, depending on the anatomy being treated, this may addfurther challenges to accurate stent delivery. In certain parts of theanatomy, exact placement of the stent is critical to the successfulclinical outcome of the procedure. For example, percutaneous coronaryintervention (PCI) in ostial coronary artery lesions has beentechnically difficult because the stent is preferably precisely deployedin the ostium without side branch compromise. A similar level ofaccuracy is needed with ilio-femoral and ilio-caval stenting as isroutinely used for the treatment of iliac vein compression syndrome(IVCS) and post-thrombotic syndrome (PTS) whereby the profunda and theinferior vena cava can be partially or completely blocked (or “stentjailed”) by the stent if the stent is not placed accurately afterdeployment. Other examples where precise placement of the stent areimportant include but are not limited to any number of arterialapplications, esophageal stenting of gastric varices, transjugularintrahepatic portosystemic shunt (TIPS) stenting for relief of portalhypertension, and use of endovascular stent-grafts for arterialaneurysms (e.g. AAA, femoral, popliteal).

Additionally, depending on the direction from which the deliverycatheter approaches the treatment site, it may be desirable to deploythe stent in a preferred direction. Physicians may enter the bodythrough different access sites, e.g. femoral vein or artery, theinternal jugular vein (IJV), etc. before inserting the stent deliverysystem through the bodily lumens to the target location. Because thestent delivery system will be in different orientations depending on thephysician's choice for access site, it may be necessary for the deliverysystem to have the correct stent release mode, such as proximal ordistal release of the stent. It would therefore be advantageous for adelivery system to allow both release modes such that the operator (e.g.physician), can use the same system with either approach. With thetypical commercially available stent delivery system, the operator islimited to one approach due to the distal release of the stent.Physician technique in stenting can also dictate which release is usedin a procedure. For example, in the case of iliofemoral stenting with afemoral approach the user may choose to deploy and overlap multiplestents of varying sizes using proximal release such that the smallerdiameter stent is placed first and the amount of overlap with thesecondary stent(s) is tightly controlled.

In situations where multiple stents are delivered, it may be desirableto selectively deploy the stents. For example, abdominal aortic aneurysm(AAA) stent-grafts can be constructed of multiple components—trunk ormain body, bifurcated main, main extension, limb extensions, steppedlimbs, flared limbs, etc. Because each component is placed and deployedwith a preferred release, one bi-directional deployment system withmultiple stents, or stent grafts, or components could serve the functionof numerous standard delivery systems. The deployment of the stents orcomponents can be any combination of proximal or distal releases. Thistype of stenting can be useful in other areas of the body wherebifurcations are present as well.

Furthermore, operators may require bi-directional deployment in caseswhere the target location is bookended by anatomical features thatrequire exact stent placement of both the distal and proximal ends ofthe stent. Two bi-directional deployment systems may be used with oneemploying the distal release and the other employing the proximalrelease. The non-critical ends of each of the deployed stents wouldoverlap with each other in the middle of the target location. Withoutbi-directional deployment capability, an operator would face thelikelihood of understenting, overstenting, or inaccurate stent placementand suboptimal results because of the inexact lengths of stent availableto treat an exact length of disease. As mentioned earlier, ilio-femoraland ilio-caval stenting of the venous system may require the user tostent entirely from the confluence of the inferior vena cava to theprofunda of the leg. A distal release is preferred for accurate stentdeployment at the confluence, whereas a proximal release is preferred soas to avoid “stent jailing” of the profunda. In lieu of performing thisprocedure with two bi-directional deployment systems, anotherbi-directional deployment device embodiment loaded with two stents (onedeployable with distal release and one deployable with proximal release)could greatly simplify this type of procedure.

Therefore, it would be desirable to deploy a stent from its distal endtoward its proximal end, as is traditionally done in many conventionalstent procedures. In other cases, it would be desirable if the stentcould be deployed from its proximal end toward its distal end. In thecase where multiple stents are deployed, it would be desirable if afirst stent could be deployed in a first direction, and a second stentdeployed in a second direction that may be the same or different thanthe first direction. Thus, improved stent delivery systems such as abi-directional stent deployment system, also referred to as bi-modal, orselectively deployable stent delivery system would be advantageous.Additionally, since there currently are no FDA approved and commerciallyavailable stents and delivery systems for treating venous outflowobstruction, there is need for such devices and methods of use. At leastsome of these objectives will be met by the inventions described herein.

2. Description of the Background Art

Relevant patent applications include U.S. patent application Ser. No.12/903,056, filed Oct. 12, 2010, the entire contents of which areincorporated herein by reference. Other relevant patents andpublications include U.S. Pat. Nos. 7,137,993; 6,849,084; 6,716,238;6,562064; 5,873,907; and U.S. Patent Publication Nos. 2009/0264978;2004/220585; 2002/120323; and 2002/188341.

BRIEF SUMMARY OF THE INVENTION

The present invention relates generally to medical devices, and moreparticularly to endoluminal delivery systems for prostheses such asstents, or other implantable structures. The delivery systems may beused for placement of a stent in the arterial system, the venous system,or any other portion of the body.

In a first aspect of the present invention, a bi-directional stentdelivery system comprises an inner elongate shaft having a proximalportion and a distal portion, and a radially expandable prosthesisdisposed over the inner elongate shaft. The prosthesis has a radiallycollapsed configuration and a radially expanded configuration. In thecollapsed configuration the prosthesis is adapted to be deliveredthrough a patient's vasculature, and in the expanded configuration theprosthesis engages a vessel wall or other tissue. An outer elongateshaft has a proximal portion and a distal portion. A shuttle sheath hasa proximal portion and a distal portion. The shuttle sheath is disposedover the radially expandable prosthesis. The distal portion of the innershaft is releasably coupled to the distal portion of the shuttle sheath,and the distal portion of the outer shaft is releasably coupled theproximal portion of the shuttle sheath. Distal advancement of the innershaft advances the shuttle sheath distally when the outer shaft isuncoupled from the shuttle sheath, thereby allowing the prosthesis toradially expand from a proximal end thereof to a distal end thereof.Proximal retraction of the outer shaft retracts the shuttle sheathproximally when the inner shaft is uncoupled from the shuttle sheath,thereby allowing the prosthesis to radially expand from a distal endthereof to a proximal end thereof.

The inner shaft may comprise a lumen extending between the proximal anddistal portions that is configured to slidably receive a guidewire. Theprosthesis may comprise a first stent. A second stent may also beincluded with the system, and the second stent may be unattached andaxially separated from the first stent by a gap. The stents may beself-expanding, balloon expandable, or a combination thereof. The stentsmay be fabricated from a nickel titanium alloy such as nitinol.

The outer shaft may comprise a lumen extending between the proximal anddistal portions thereof. The shuttle sheath may have a length that isequal to or greater than the length of the radially expandable stent orstents. The shuttle sheath may constrain the prosthesis alongsubstantially its entire length. The shuttle sheath may have a proximalend, a distal end, and a lumen extending therebetween. The shuttlesheath may comprise a substantially cylindrical sheath.

The system may further comprise a distal coupling mechanism thatreleasably couples the distal portion of the inner shaft to the distalportion of the shuttle sheath. The distal coupling mechanism maycomprise a threaded or helical region on the distal portion of the innershaft and a corresponding threaded or helical region on the distalportion of the shuttle sheath. The distal coupling mechanism maycomprise one or more of a snap fit, an interference fit, a barbedconnector, a locking mechanism, a rotatable key lock, a linear key lock,a threaded bushing, a twist lock, a magnetic coupling, a bayonetcoupling, or a frangible connector. The system may further comprise aproximal coupling mechanism that releasably couples the distal portionof the outer shaft to the proximal portion of the shuttle sheath. Theproximal coupling mechanism may comprise a threaded or helical region onthe distal portion of the outer shaft and a corresponding threaded orhelical region on the proximal portion of the shuttle sheath. Theproximal coupling mechanism may comprise one or more of a snap fit, aninterference fit, a barbed connector, a locking mechanism, a rotatablekey lock, a linear key lock, a threaded bushing, a twist lock, amagnetic coupling, a bayonet coupling, or a frangible connector.

The inner shaft may be threadably or helically engaged with the shuttlesheath, and the outer shaft may also be threadably or helically engagedwith the shuttle sheath. The threads or helix engaging the inner shaftwith the shuttle sheath may have a first orientation, and the threads orhelix engaging the outer shaft with the shuttle sheath may have a secondorientation opposite of the first orientation such that rotation of theinner shaft in a first direction couples the inner shaft with theshuttle sheath and rotation of the inner shaft in a second directionopposite the first direction disengages the inner shaft from the shuttlesheath. Additionally rotation of the outer shaft in the first directionmay disengage the outer shaft from the shuttle sheath and rotation ofthe outer shaft in the second direction may engage the outer shaft withthe shuttle sheath. The inner shaft may be coupled to the shuttle sheathwith a bayonet coupling mechanism that has a slot in a firstorientation, and the outer shaft may be coupled with the shuttle sheathwith a second bayonet coupling mechanism having a slot in a secondorientation opposite the first slot. Rotation of the inner shaft in afirst direction may couple the inner shaft with the shuttle sheath androtation of the inner shaft in a second direction opposite the firstdirection may disengage the inner shaft from the shuttle sheath.Rotation of the outer shaft in the first direction may disengage theouter shaft from the shuttle sheath and rotation of the outer shaft inthe second direction may engage the outer shaft with the shuttle sheath.

The system may further comprise a middle shaft concentric with the innerand the outer shafts, and disposed therebetween. The prosthesis may bedisposed over the middle shaft and in direct engagement therewith. Themiddle shaft may comprise an outer surface that is substantially smooth.The middle shaft may comprise a proximal stent stop and a distal stentstop. The proximal stop may be disposed proximally of a proximal end ofthe prosthesis, and the distal stopping element may be disposed distallyof a distal end of the prosthesis. The proximal stopping element mayprevent proximal movement of the prosthesis, and the distal stoppingelement may prevent distal movement of the prosthesis. The proximalstopping element or the distal stopping element may comprise one or moreof a ring, a band, a step, a bushing, or a sleeve, that prevent proximalor distal movement of the prosthesis.

The system may also comprise an actuator mechanism disposed near aproximal end of the delivery system. The actuator mechanism may beoperably coupled with the inner and outer shafts, thereby allowing anoperator to couple and uncouple the inner and outer shafts with theshuttle sheath. The actuator mechanism may also be configured toslidably or rotatably move the inner and the outer shafts bothproximally and distally. The system may further comprise anintravascular ultrasound device configured to allow visualization of theprosthesis and surrounding tissue.

In another aspect of the present invention, a bi-directional method fordeploying a prosthesis at a treatment site in a patient comprisesproviding a delivery catheter comprising a prosthesis having a proximalend and a distal end, the prosthesis in a collapsed configuration anddisposed on the delivery catheter. The prosthesis is delivered to thetarget treatment site, and a deployment direction for the prosthesis isselected. The deployment direction comprises radially expanding theprosthesis from the proximal end thereof to the distal end thereof, andradially expanding the prosthesis from the distal end thereof to theproximal end thereof. A constraint is removed from the prosthesisthereby permitting the prosthesis to radially expand in the selecteddeployment direction. The prosthesis radially expands from the collapsedconfiguration to an expanded configuration in the selected deploymentdirection so that the expanded prosthesis engages tissue at the targettreatment site. The delivery catheter is withdrawn from the patient andthe prosthesis is left deployed in the patient at the target treatmentsite.

Delivering the prosthesis may comprise advancing the delivery catheterthrough vasculature of the patient to the target treatment site. Thedelivery catheter may have a proximal end, a distal end, and a lumentherebetween. Delivering the prosthesis may comprise slidably advancingthe delivery catheter over a guidewire disposed in the lumen. Deliveringthe prosthesis may comprise positioning the prosthesis in a vein, suchas the iliac vein.

The delivery catheter may comprise an inner elongate shaft and a shuttlesheath disposed over the prosthesis. Selecting the deployment directionfor the prosthesis may comprise coupling the inner elongate shaft withthe shuttle sheath, distally advancing the inner elongate shaft distallythereby advancing the shuttle sheath distally away from the prosthesis,and radially expanding the prosthesis from the proximal end thereof tothe distal end thereof. Coupling the inner elongate shaft with theshuttle sheath may comprise threadably or helically engaging the innerelongate shaft with the shuttle sheath or coupling them together with abayonet coupling. The delivery catheter may further comprise an outerelongate shaft, and selecting the deployment direction may comprisedecoupling the outer elongate shaft from the shuttle sheath. Decouplingthe outer elongate shaft from the shuttle sheath may comprise threadablyor helically disengaging the outer elongate shaft from the shuttlesheath. Decoupling may comprise releasing a bayonet coupling between theouter elongate shaft and the shuttle sheath.

The delivery catheter may comprise an outer elongate shaft and a shuttlesheath disposed over the prosthesis. Selecting the deployment directionfor the prosthesis may comprise coupling the outer elongate shaft withthe shuttle sheath, proximally retracting the outer elongate shaftthereby retracting the shuttle sheath proximally away from theprosthesis, and radially expanding the prosthesis from the distal endthereof to the proximal end thereof. Coupling the outer elongate shaftwith the shuttle sheath may comprise threadably or helically engagingthe outer elongate shaft with the shuttle sheath. Coupling may comprisecoupling the inner elongate shaft and the shuttle sheath with a bayonetcoupling. The delivery catheter may further comprise an inner elongateshaft, and selecting the deployment direction may comprise decouplingthe inner elongate shaft from the shuttle sheath. Decoupling the innerelongate shaft from the shuttle sheath may comprise threadably orhelically decoupling the inner elongate shaft from the shuttle sheath.Decoupling may comprise releasing a bayonet coupling between the outerelongate shaft and the shuttle sheath.

The delivery catheter may comprise a shuttle sheath that is disposedover the prosthesis, and removing the constraint may comprise distallyadvancing the shuttle sheath away from the prosthesis so that theprosthesis is unconstrained from radial expansion in a directionextending from the proximal end of the prosthesis to the distal end ofthe prosthesis. The delivery catheter may comprise a shuttle sheathdisposed over the prosthesis, and removing the constraint may compriseproximally retracting the shuttle sheath away from the prosthesis sothat the prosthesis is unconstrained from radial expansion in adirection extending from the distal end of the prosthesis to theproximal end of the prosthesis.

Radially expanding the prosthesis may comprise self-expanding a stent.Withdrawing the delivery catheter from the patient may comprisewithdrawing the delivery catheter from the patient's vasculature. Theprosthesis may comprises two prostheses, and the method may compriseselecting a first deployment direction for the first prosthesis,radially expanding the first prosthesis in the first deploymentdirection, and radially expanding the second prosthesis in a seconddeployment direction opposite of the first deployment direction. Themethod may comprise visualizing the expanded prosthesis with varioustechniques including ultrasound or fluoroscopy. The method may alsocomprise retracting the radially expanded prosthesis into a shuttlesheath, repositioning the prosthesis, and radially expanding theprosthesis. The radially expanded prosthesis may be dilated with anexpandable member such as a balloon.

These and other embodiments are described in further detail in thefollowing description related to the appended drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D illustrate an exemplary embodiment of a bi-directional stentdelivery catheter configured for distal stent release.

FIGS. 2A-2D illustrate the embodiment of FIGS. 1A-1D configured forproximal stent release.

FIGS. 3A-3E illustrate an exemplary embodiment of a bi-directional stentdelivery catheter configured for distal stent release.

FIGS. 4A-4E illustrate the embodiment of FIGS. 3A-3E configured forproximal stent release.

FIGS. 5A-5F illustrate an exemplary embodiment of a bi-directional stentdelivery catheter for delivery of multiple stents.

FIGS. 6A-6C illustrate an exemplary method of stenting a vessel withdistal stent release.

FIGS. 7A-7C illustrate an exemplary method of stenting a vessel withproximal stent release.

FIGS. 8A-8B illustrate the basic anatomy of iliac vein compressionsyndrome.

FIG. 9 illustrates overlapping of two or more stents.

FIG. 10A-10E illustrates exemplary embodiments of threaded couplingmechanisms.

FIG. 10F illustrates an exemplary embodiment of a bayonet couplingmechanism.

FIGS. 10G-10H illustrate another exemplary embodiment of a bayonetcoupling mechanism.

FIGS. 11A-11C illustrate exemplary embodiments of snap fits.

FIGS. 11D-11E illustrate still other embodiments of snap or press fitmechanisms.

FIG. 12 illustrates yet another exemplary embodiment of a couplingmechanism.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to medical devices, and moreparticularly to endoluminal delivery systems for prostheses such asstents, or other implantable structures. The delivery systems may beused for placement of a stent in the arterial system, the venous system,or any other portion of the body. The use of stents and otherimplantable medical devices such as grafts, stent-grafts, filters,shunts, valves, etc., are referred to herein as prostheses. Prosthesesmay be used to deliver drugs to tissue, support tissue, or maintainpatency of bodily lumens, as well as performing other functions, andhave been widely reported in the scientific and patent literature.

FIGS. 1A-1D and FIGS. 2A-2D illustrate a first exemplary embodiment of abi-directional delivery system for a prosthesis. Delivery of a stentwill be described, however, one of skill in the art will appreciate thatthe system may be used to deliver other prosthesis such as grafts, stentgrafts, filters, etc. FIGS. 1A-1D illustrate distal release of a stentwhere the stent is deployed such that the stent expands from its distalend toward its proximal end. FIGS. 2A-2D illustrate proximal release ofa stent where the stent is deployed such that the stent expands from isproximal end toward its distal end.

FIG. 1A illustrates a stent delivery system 100 which is configured topreferentially deploy a stent distally. The delivery system 100 includesan inner shaft 102, a middle shaft 108, and outer shaft 114, a shuttlesheath 120 and a stent 128. The shafts may be extruded tubes preferablyhaving circular cross sections, or other cross sections are contemplatedsuch as oval, rectangular, elliptical, etc. The shafts in this and otherembodiments described below may be fabricated from polyethylene, PTFE,FEP, PVC, or other materials known in the art. The inner shaft 102 has acentral lumen extending from its proximal end to its distal end forfluids such as contrast media or for slidably receiving a guidewire (notillustrated). A distal tapered nosecone 126 is coupled with inner shaft102 and prevents trauma to the vessel or other tissue during delivery. Ahub 106 or flared region provides the user a region for grasping, andalso provides a stop for preventing the inner shaft from being advancedtoo far distally into the middle shaft 108 (or retracting the middleshaft too far proximally). The middle shaft 108 also has a central lumen110 extending between its proximal and distal ends, and the middle shaft108 is slidably disposed over the inner shaft 102. The middle shaft 108also has a hub 112 or flared region that provides the user a region forgrasping, as well as providing a stop to prevent the middle shaft 108from being advanced too far distally into the outer shaft 114 (orretracting the outer shaft 114 too far proximally). The middle shaft 108is slidably disposed over the inner shaft 102, and slidably disposed inthe outer shaft 114 and also slidably disposed in the shuttle sheath120. This embodiment and others described below are configured for overthe wire use, although one of skill in the art will appreciate that thedelivery catheters may easily be modified to allow rapid exchange usewith a guidewire. Rapid exchange and over the wire use are welldescribed in the patent literature, such as in U.S. Pat. No. 5,451,233.Additionally, the various hubs 106, 112, 118 may include hemostasisvalves which allow the shafts to move relative to one another whilepreventing blood or other fluids from exiting the proximal portion ofthe delivery catheter. A hemostasis valve such as a Tuohy-Borst may alsobe used to tighten down on a shaft to prevent the shaft from movingrelative to another shaft. Therefore, the Tuohy-Borst may be used as alocking mechanism as well.

A stent 128 is disposed over the middle shaft 108 in a collapsedconfiguration sized for delivery. A pair of stops 130, 132 prevent thestent 128 from moving proximally or distally along the middle shaft 108during delivery and deployment. The stops 130, 132 may be rings, bands,steps, bushings, sleeves, bumps, flanges, raised annular sections, orother structures which prevent the stent 128 from sliding along themiddle shaft 108. The stops 130, 132 may be radiopaque to allowvisualization of the proximal and distal ends of the stent underfluoroscopy during the stent procedure. Other visualization techniquesmay also be used such as x-ray, endoscopy, IVUS, MRI, ultrasound, andCT, as well as other techniques. Stent 128 is preferably a selfexpanding stent and therefore shuttle sheath 120 is disposed over thestent 128 in order to constrain it and prevent radial expansion thereof.The stent 128 may be fabricated from self expanding or shape memoryalloys such as nitinol, spring steels, resilient polymer, or othermaterials known in the art. The shuttle sheath 120 is at least as longor longer than the length of the stent 128.

Outer shaft 114 also has a central lumen 116 extending between theproximal and distal ends of the shaft 114 so that the middle shaft 108may be slidably disposed therein. A hub 118 on the proximal end of theouter shaft 114 provides the user a region for grasping, and alsoprevents the hub 112 on the middle shaft 108 from being advanced too fardistally (or prevents the outer shaft 114 from being retractedproximally too far).

A proximal lock or coupling mechanism 122 couples the distal end of theouter shaft 113 with the proximal end of the shuttle sheath 120. Adistal lock or coupling mechanism 124 couples distal end of the shuttlesheath 120 with the distal end of the inner shaft 102 via nosecone 126.The proximal and distal locks or coupling mechanisms may take a numberof forms, including for example, snap fits, interference fits, barbedconnectors, locking mechanisms, key locks, rotational or linear locks,threaded bushings, twist locks, magnetic couplings, bayonet coupling,breakable or frangible connectors, as well as others known in the art.The proximal coupling may take the same form as the distal coupling, ordifferent couplings may be used on the proximal and distal ends. In thisembodiment, the proximal lock 122 is locked (as indicated by thedarkened rectangle 122), and the distal lock 124 is unlocked (asindicated by the white rectangle 124). This configuration allowspreferential distal delivery of stent 128 as illustrated in FIGS. 1B-1D.

In FIG. 1B, the outer shaft 114 is retracted proximally relative to themiddle shaft 108 and the inner shaft 102. Because outer shaft 114 islocked with shuttle sheath 120, and shuttle sheath 120 is unlocked frominner shaft 102, as the outer shaft 114 is proximally retracted, shuttlesheath 120 will also be proximally retracted. FIG. 1C shows that asshuttle sheath 120 is proximally retracted, stent 128 become partiallyunconstrained, allowing stent 128 to self expand into its radiallyexpanded configuration. In this partially expanded configuration, aphysician may optional re-advance the shuttle sheath 120 distally inorder to draw the stent 128 back into a collapsed configurationconstrained by shuttle sheath 120. This allows the stent to berepositioned if the initial deployment is not optimal. As shuttle sheath120 continues to move proximally, stent 128 will also continue to selfexpand from its distal end toward its proximal end. FIG. 1D shows thatonce shuttle sheath 120 is fully retracted proximally and stent 128 iscompletely unconstrained, stent 128 fully expands into its radiallyexpanded configuration. The delivery catheter 100 may then be retractedproximally through expanded stent 128 and removed from the patient. Ahandle (not illustrated) may be provided on the proximal end of thecatheter with various actuation mechanisms (e.g. rotating knobs, slidinglevers, etc.) to facilitate actuation of the shafts relative to oneanother. The handle may also be used with other embodiments disclosedherein. This delivery method may be used with a typical antegradefemoral vein approach. Distal release may also be used for stentingabove the origin of the profunda when using a retrograde approach.

FIGS. 2A-2D illustrate the delivery system 100 configured preferentiallyfor proximal delivery of a stent. FIG. 2A shows the delivery system 100that is substantially the same as previously described above withrespect to FIGS. 1A-1D, except the major difference being that theconfiguration of the proximal and distal locks or couplings 122, 124 hasbeen reversed. In this exemplary embodiment, the distal lock 124 is nowin a locked configuration such that shuttle sheath 120 is coupled withinner shaft 102 via nosecone 126. The locked configuration is indicatedby the blackened rectangle 124. Proximal lock 122 is unlocked, thereforethe shuttle sheath 120 is uncoupled from the outer shaft 114, asindicated by the white rectangle 122.

In FIG. 2B, the inner shaft 102 is advanced distally thereby alsodistally advancing shuttle sheath 120 relative to stent 128, as seen inFIG. 2C. As shuttle sheath 120 advanced distally, stent 128 becomesunconstrained, thereby allowing the unconstrained portion of stent 128to self expand from its proximal end toward its distal end, into itsradially expanded configuration. Additionally, when stent 128 is in apartially expanded configuration as shown in FIG. 2C, a physicianoptionally may proximally retract inner shaft 102 thereby retractingshuttle sheath 120 over stent 128 to recapture the stent andre-constrain the stent 128 in its collapsed configuration. This allowsthe physician to reposition the stent when its initial deployment is notoptimal. FIG. 2D illustrates the stent 128 in its fully expandedconfiguration after shuttle sheath has been advanced distally so thatstent 128 is unconstrained. The catheter 100 may then be retracedproximally through expanded stent 128 and removed from the patient. Thismethod of delivery may be used during a contralateral retrograde venousapproach or a jugular approach. Placement of the stent above the originof the profunda vein is critical, therefore proximal release may also beused when using an antegrade approach.

In the examples illustrated in FIGS. 1A-1D and FIGS. 2A-2D, the proximaland distal locks or coupling mechanisms 122, 124 are pre-set to a lockedor unlocked configuration. One of skill in the art will appreciate thatany combination of locked and unlocked configurations is possible.Therefore the catheter may be supplied with both locks in the lockedposition, or both in the unlocked position. Also, the catheter may besupplied with proximal lock locked and the distal lock unlocked, or thecatheter may be supplied with the proximal lock unlocked and the distallock locked. The user may use the catheter as supplied, or the lockconfiguration may be changed by the user either prior to using thecatheter, or in situ, depending on the desired stent deploymentdirection. Examples of various locking mechanisms application to thisembodiment as well as the other embodiments disclosed herein aredescribed in greater detail below.

FIGS. 3A-3E illustrate another exemplary embodiment of a bi-directionalstent delivery system. The delivery system 300 may be used for eitherproximal or distal stent delivery depending on how the shafts areactuated. FIG. 3A illustrates the delivery system 300 prior to use inits preferred configuration. The system 300 includes an inner shaft 302,a middle shaft 308, an outer shaft 314, a shuttle sheath 320, and astent 328. Each of the shafts 302, 308, 314 have a lumen extendingbetween the proximal and distal ends of the shaft to allow the shafts toslidably receive one another and slidably move relative to one another.For example, inner shaft 302 is slidably disposed in the lumen of middleshaft 308, and middle shaft is slidably disposed in the lumen of outershaft 314. Additionally, each shaft 302, 308, 314 also has a hub orflanged region 306, 312, 318 near the proximal end of the shaft andprovides a region for an operator to grasp, as well as providing a stopto prevent the shafts from moving too far into one another. Otheraspects of the hubs are generally similar to those previously described.

Stent 328 is constrained and held in a radially contracted configurationon the middle shaft 308 by shuttle sheath 320. Stent stops 330, 332generally take the same form as those previously described above inFIGS. 1A-1D and 2A-2D. The stops 330, 332 prevent unwanted axialmovement of stent 328 relative to middle shaft 308. A lock or couplingmechanism 324 couples the distal end of shuttle sheath 320 with theinner shaft 302 via nose cone 326. In this preferred embodiment, thelock is closed (as indicated by the darkened rectangle) so that shuttlesheath 320 is connected to inner shaft 302 via nose cone 326. The stent328 generally takes the same form as stent 128 previously describedabove.

In FIG. 3B the inner shaft 302 is advanced distally. Because lock 324 isclosed, shuttle sheath 320 will also move distally. As the shuttlesheath 320 is advanced distally, stent 328 will become unconstrained andwill start to self-expand slightly until further expansion isconstrained by outer shaft 314. As inner shaft 302 is further advanceddistally, stent 328 becomes completely unconstrained and self expandsinto engagement with outer shaft 314 where further self expansion isprevented, as shown in FIG. 3C.

Outer shaft 314 may then be proximally retracted as illustrated in FIG.3D. Proximal retraction of outer shaft 314 releases the constraint onstent 328 so that the stent may then self expand into its radiallyexpanded configuration proximally. In FIG. 3D, the stent 328 ispartially expanded and partially constrained. In this configuration, theoperator may optionally re-advance the outer shaft 314 to recapture andreconstrain stent 328 into a collapsed configuration. This allows thestent 328 to be repositioned and redeployed if the initial position wasnot optimal. The outer shaft 314 is then fully retracted proximally sothat stent 328 is fully unconstrained, and stent 328 radially expandsinto its fully expanded configuration. Catheter 300 may then beproximally retracted through the stent 328 and removed from the patient.

The lock 324 in FIGS. 3A-3E is preferably in the locked configuration sothat proximal or distal movement of the inner shaft 302 willcorrespondingly move the shuttle sheath 320. One of skill in the artwill appreciate that the catheter may be provided with the lock in theunlocked configuration, and the user may lock it as desired.

FIGS. 4A-4E illustrate how delivery catheter 300 in FIGS. 3A-3E may alsobe used for proximal stent deployment. The delivery system 300 in FIGS.4A-4E is the same as the system described above in FIGS. 3A-3E, exceptthat the order of shaft actuation is different, thereby allowing stentdeployment in the opposite direction.

FIG. 4A shows the stent delivery system 300 prior to use. In FIG. 4B,the outer shaft 314 is proximally retracted until the shuttle sheath 320is unconstrained by the outer shaft 314, as seen in FIG. 4C. In FIG. 4D,the inner shaft 302 is advanced distally. Because lock 324 is lockedwith shuttle sheath 320 via nose cone 326, the shuttle sheath 320 willalso be advanced distally, thereby allowing stent 328 to self expand asthe constraint provided by shuttle sheath 320 is removed. Also, aspreviously mentioned, while the stent is partially expanded, a physicianmay optionally recapture the stent and reposition it when the initialdeployment is not optimal. The stent 328 may be recaptured by retractingthe inner shaft 302, thereby also proximally retracting shuttle sheath320 so that stent 328 returns to its collapsed configuration constrainedby shuttle sheath 320. In FIG. 4E, the inner shaft is advanced distallyso that shuttle sheath 320 is removed from stent 328. Stent 328 is thenunconstrained and can radially expand fully into its expandedconfiguration. Delivery catheter 300 may then be retracted proximallythrough stent 328 and removed from the patient.

FIGS. 5A-5F illustrate another exemplary embodiment of a bi-directionalstent delivery system 500. This embodiment is similar to that previouslydescribed above in FIGS. 1A-1D and FIGS. 2A-2D, with the majordifference being that this embodiment delivers two stents, onepreferably with proximal release and the other preferably with distalrelease. FIG. 5A shows stent delivery system 500 having an inner shaft502, a middle shaft 508, an outer shaft 514, a shuttle sheath 520, andtwo stents 528, 529. All three shafts 502, 508, 514 have a central lumenextending between the proximal and distal ends of the shafts in order toallow the shafts to move relative to one another. Inner shaft 502 isslidably disposed in the lumen of middle shaft 508, and middle shaft 508is slidably disposed in the lumen of outer shaft 514. Also, a hub orflanged region 506, 512, 518 on the proximal end of each shaft 502, 508,514 provides a region for the physician to grasp during usage andactuation, as well as providing a stop to prevent excessive shaftmovement. Moreover, in this embodiment, as well as the previousembodiments, the hubs may have standard fittings on them such as Luertapers or threaded portions for coupling with a syringe, tube, or otherdevice. Other features of the hubs previously described may also beemployed in this embodiment.

Stents 528, 529 are disposed over middle shaft 508, and stent stops 530,531, 532 prevent unwanted axial movement of the stents along the middleshaft 514. The stents 528, 529 and stent stops 530, 531, 532 generallytake the same form as those previously described above. Locks orcoupling mechanisms 522, 524 couple the shuttle sheath 520 with eitherthe inner shaft 502 or the outer shaft 514 as will be described ingreater detail below. In FIG. 5A, lock 524 is closed or locked (asindicated by the darkened rectangle) such that shuttle sheath 520 isconnected to inner shaft 502 via nose cone 526. Lock 522 is unlocked (asindicated by the white rectangle) such that outer shaft 514 is free tomove relative to shuttle sheath 520.

In FIG. 5B, inner shaft 502 is advanced distally, therebycorrespondingly advancing shuttle sheath 520 distally. As the proximalmost stent 529 becomes unconstrained, it partially self expands into itsradially expanded configuration. At this point, the physician mayoptionally retract the inner shaft 502 to recapture and constrain thestent 529 into its radially collapsed configuration if repositioning isdesired. Otherwise, the inner shaft 502 is advanced distally until stent529 becomes fully unconstrained and it radially expands into itsexpanded configuration as illustrated in FIG. 5C. Inner shaft 502 mayfurther be advanced distally to permit distal release the distal moststent 528, or as seen in FIG. 5D, the inner shaft is proximallyretracted and the distal lock or connector 524 is unlocked (illustratedby the white rectangle) and the proximal lock or connector 522 is locked(illustrated by the darkened rectangle).

In FIG. 5E the outer shaft 514 is then retracted proximally, therebyalso proximally retracting shuttle heath 520 so that stent 528 becomesunconstrained. This permits stent 528 to radially self expand. While thestent 528 is partially expanded and partially collapsed, the outer shaft514 may optionally be advanced distally to recapture and reconstrain thestent 528 in the radially collapsed configuration in case repositioningis desired. Otherwise, as seen in FIG. 5F, the outer shaft 514 isfurther retracted proximally until stent 528 is no longer constrained,and it self-expands into the radially expanded configuration, in aproximal direction (opposite of the first stent 529). Delivery system500 may then be retracted proximally through stents 528, 529 and removedfrom the patient.

In this embodiment, one of skill in the art will appreciate that anyorder of stent deployment may be used. For example, both stents may bedeployed proximally, or both may be deployed distally. In still otherembodiments, the proximal stent may be deployed proximally while thedistal stent is deployed distally. In yet other embodiments the proximalstent may be deployed distally, and the distal stent may be deployedproximally. Deployment direction will depend on the order of actuationof the shafts and the coupling and uncoupling of the shuttle sheath withthe inner and outer shafts. Furthermore, any number of stents may becarried by the delivery system, and the exemplary embodiment is notintended to limit the system to delivery of two stents.

Any of the embodiments described above may have a number of differentlocking mechanisms or couplings that releasably join the shuttle sheathwith the either the inner shaft or the outer shaft. For example, FIG.10A illustrates how threaded couplings may be used. The deliverycatheter 1002 includes an outer shaft 1004, inner shaft 1018, shuttlesheath 1010, and nose cone 1016 coupled to the inner shaft 1018. Themiddle shaft and stent described in embodiments above have been omittedfor clarity. The outer shaft 1004 includes a threaded distal portion1006 and the proximal portion of shuttle sheath 1010 also includes athreaded portion 1008. The distal portion of the shuttle sheath 1010also includes a threaded portion 1012, and a proximal portion of nosecone 1016 includes a threaded portion 1014. The outer shaft 1004 may berotated and advanced distally relative to the shuttle sheath 1010thereby threadably engaging the outer shaft 1004 with the shuttle sheath1010. Similarly, the inner shaft 1018 may be rotated and retractedproximally relative to the shuttle sheath, thereby threadably engagingthe nose cone 1016 and inner shaft 1004 with the shuttle sheath 1010.The threads may be in same direction, or preferably are in differentdirections so that rotation in one direction couples the shuttle sheathwith one of the shafts, and uncouples the shuttle sheath with theremaining shaft. Similarly rotation in the opposite direction uncouplesthe sheath from one shaft, and couples it with the remaining shaft. Thethreads often are either left handed or right handed. Additionally, insystems where the couplings are pre-set, the couplings may be uncoupledor coupled together. Male or female threads may be interchanged on theshuttle sheath and corresponding shaft.

FIGS. 10B-10E illustrate exemplary embodiments of threaded couplingswhich may be used on either end of the shuttle sheath, the inner shaft,or outer shaft to create the coupling mechanism in any of theembodiments described herein. For example, FIG. 10B illustrates athreaded tube 1050 with internal threads 1052, and FIG. 10C illustratesa threaded nut 1054 also with internal threads 1056. Threaded rods suchas in FIGS. 10D-10E may be threadably engaged with the embodiments ofFIGS. 10B-10C. FIG. 10D illustrates a threaded rod 1058 having externalthreads and a central channel 1060 extending through the threaded rod.FIG. 10E illustrates another threaded rod 1062 having external threads,but having a solid center 1064.

Another exemplary embodiment of a coupling or locking mechanism that maybe used with any of the embodiments of delivery systems described aboveis illustrated in FIG. 10F. In this embodiment, a bayonet coupling,sometimes also referred to as a screw-snap connector, or BNC connectoris used to releasably couple the shuttle sheath with either the innershaft or the outer shaft, or both. The bayonet coupling includes afemale connector 1026 and a male connector 1036. The female connector1026 includes a central channel 1040 and at least one, and preferablytwo or more slotted channels 1028 that extend through a sidewall of thefemale connector 1026. The slotted channel 1028 has a linear portion1030 which is generally parallel to the longitudinal axis of theconnector 1026, a transverse portion 1032 which is disposed at an anglerelative to the linear portion 1030, and a receiver 1034. The maleconnector 1036 includes an elongate distal portion 1038 that may bereceived in the central channel 1040 of the female connector 1026. Atleast one, and preferably two or more pins 1042 extend radially outwardfrom the elongate distal portion 1038. In use, the male connector 1036is inserted into the female connector 1026 such that the elongate distalportion 1038 is received in the central channel 1040. The pins 1042 arealigned with the linear portion 1030 of slot 1028, thus as the maleconnector is inserted into the female connector, the pin is advancedalong the linear portion of the slot until it reaches the end of thelinear portion. The male connector is then rotated relative to thefemale connector so that the pin then advances along the transverseportion of the slot until it reaches the end of transverse portion. Aspring (not illustrated) is often included in the bayonet coupling, andthis forces the male connector away from the female connector so thatpin 1042 then nests in receiver 1034, locking the male and femaleconnectors together. The two may be released from one another bypressing the male connector inward relative to the female connector androtating the two relative to one another so that the pin slides outwardalong the transverse portion and then the two connectors are pulledapart relative to one another so that pin 1042 is released from thelinear portion of the slot. Either the male or female connector may beused on one end of the shuttle sheath, with the opposite connector usedon the inner or outer shaft to which the shuttle sheath is releasablyconnected. Additionally, just as threads have “handedness,” the bayonetcoupling may also have left-handed and right-handed mechanisms such thatrotation in one direction releases the connector, while rotation in theopposite direction couples the connector. Thus a left handed bayonetcoupling may be used on one end of the shuttle sheath, while a righthanded bayonet coupling may be used on the opposite end of the shuttlesheath. This allows one end of the shuttle sheath to be connectedwithout connecting the opposite end.

FIGS. 10G-10H illustrate another exemplary embodiment of a bayonetcoupling. This embodiment is similar to the previous bayonet coupling inFIG. 10F, but instead of having two pins that mate with two slots, thisembodiment has four pins that mate with four slots. FIG. 10G illustratesthe male connector 1076 that is generally cylindrical and having fourpins 1078 that extend radially outward from the body of the connector.The pins are preferably spaced 90 degrees apart, but this is notintended to be limiting. The female connector 1082 includes four slots1084, preferably spaced 90 degrees apart. The slots receive the pins1078 when the male connector is inserted into the female connector androtated relative to one another. Other aspects of the male and femaleconnector, and their operation generally take the same form as describewith respect to FIG. 10F above. FIG. 10H illustrates an exemplary methodof forming the slotted female connector from a flat sheet. The slots1084 may be machined (e.g. by EDM, photochemically etched, laser cut,etc.) into a flat sheet of material that is then rolled into acylindrical shape to form the female connector. The female connector mayalso be cut from a tube. The male connector may be formed by pressfitting, bonding, welding, etc. pins into the male connector or machinedor molded.

Other connectors include frangible connectors fabricated from breakablewires, strands, fibers, tubes, tabs, hooks, barbs, cantilevers, etc.that remain intact and connected until a certain force is applied, andthe connector breaks. While these connectors are promising, they onlyallow the connection to be broken a single time, and reconnection is notpossible. Therefore preferred embodiments may be connected andunconnected multiple times. FIGS. 11A-11C also illustrate snap fitswhich may be used as the connector mechanism. FIG. 11A illustrates acantilevered snap fitting 1102 that locks with a recessed region 1104 inthe mating part. FIG. 1106 illustrates a “U” shaped cantilevered snapfit 1106, and FIG. 11C illustrates an “L” shaped cantilevered snapfitting 1108. The cantilevered snap fitting may be a part of the shuttlesheath that mates with the recessed portion on one of the shafts, or thesnap fitting may be on the shafts and the recessed portion may be a partof the shuttle sheath.

FIG. 11D illustrates yet another embodiment of a snap fit that may beused to form the connector mechanisms described above. A connectorincludes a male portion 1126 and a female portion 1132. The male portion1126 of the connector includes an elongate distal section 1128 having araised annular flange 1130 near its distal end. A plurality oflongitudinal slits 1138 form several resilient arms in the distalsection 1128 that radially expand and contract. The female connector1132 includes a proximal portion 1134 having a central channel 1136therethrough. The central channel 1136 opens up into an enlarged region1140. In use, the distal section 1128 is slidably inserted into thecentral channel 1136 forcing the resilient arms into a collapsedconfiguration. The male connector is advanced into the female connectoruntil the annular flange 1130 enters the enlarged region 1140. The armsresiliently open back up to their unbiased configuration, forcing theannular flange outward, thereby releasably locking the male and femaleconnectors together. The two may be pulled apart from one another uponapplication of adequate tensile force.

FIG. 11E illustrates a slide-on coupling mechanism which includes a maleconnector 1146 and a female connector 1140. The male connector has anelongate distal region 1148, and the female connector has a receivingportion 1142 with a central channel 1144 therethrough. The male andfemale connectors are pressed against one another such that the distalregion 1148 is received in the receiving portion 1142. The size of thetwo connectors may be adjusted to provide an appropriate friction fitagainst one another to prevent unwanted release. The two connectors maybe released from one another upon application of adequate tensile force.

FIG. 12 illustrates an exemplary embodiment of a spiral or helicalcoupling mechanism that may be used in any of the delivery catheterembodiments disclosed herein. The coupling mechanism includes a firstspiral or helical connector 1202 and a second spiral or helicalconnector 1204. The first spiral connector includes a proximal portion1206 that is preferably cylindrical and this may be joined by bonding,welding, threading, press fitting, etc. to either end of the shuttlesheath, or the inner shaft or outer shaft. A distal portion 1210 of thespiral connector winds in a spiral or helical pattern in a firstdirection to form a thread-like region. The outer diameter of the spiralconnector is preferably constant along the entire length of theconnector, but this is not intended to be limiting. Additionally, acentral channel 1214 extends through spiral connector 1202, and theinner diameter of the first connector 1202 is also preferably constantalong the connector, but not required. The second spiral connector 1204is identical to the first connector 1202, rotated 180 degrees. Thesecond connector 1204 includes a proximal portion 1208 that is alsopreferably cylindrical for joining with the shuttle sheath, inner shaft,or outer shaft by one of the methods listed above, or known to those ofskill in the art. A distal portion 1208 of the second connector 1204winds in a spiral or helical pattern in a second direction opposite thefirst direction to form a thread-like region. The outer diameter of thespiral connector 1204 is preferably constant along its entire length,but this is not meant to be limiting. Also, a central channel 1212extends through the spiral connector 1204, and the inner diameter ofsecond connector 1204 is also preferably constant along its length, butnot required. The two connectors may be joined together by rotating oneconnector relative to the other connector so that the thread-likeregions overlap and engage with one another. Also, similar to otherthreaded-type embodiments disclosed herein, when two spiral connectorsare used on opposite ends of the shuttle sheath, rotation in onedirection will couple the shuttle sheath to one of the shafts (inner orouter shaft) while decoupling the shuttle sheath from the other shaft.Similarly, rotation in the opposite direction will decouple the shuttlesheath at one end and couple it at the opposite end. The pitch of thehelix is preferably set so that rotation is smooth with relatively lowfriction and so that the number of turns required to lock the twoconnectors together is comfortable to most operators. One advantage ofthis design is that both connectors may be cut from a single piece oftubing having a length less than the combined length of the individualconnectors. Additionally, only a single connector need be manufacturedsince both halves are mirror images of one another. One connector may beused on one end of the shuttle sheath or shaft, while the same part maybe flipped over and used on the opposite end. This is desirable since ithelps reduce component inventory and ensures ease of manufacturing.

FIGS. 6A-6C illustrate an exemplary method of treating a vessel with abi-directional stent delivery system such as those described above. InFIG. 6A, the delivery catheter is advanced to a target treatment site ina vessel V. In this embodiment the treatment site is a stenotic region Sof a vein caused by compression from surrounding vessels, bone, or otheranatomical structures. The delivery catheter includes an inner shaft602, middle shaft 604, outer shaft 606, shuttle sheath 610, and proximallock 608, distal lock 612, and nose cone 614. Other aspects of thecatheter such as the proximal hubs on the shafts have been omitted forclarity. The proximal lock 608 is shown in the locked position (shownwith darkened rectangle), while the distal lock is shown in the unlockedconfiguration (shown by the white rectangle). Once the catheter isadvanced to the target treatment site, the outer sheath is proximallyretracted which also proximally retracts the shuttle sheath 610. Thestent 616 is then permitted to self expand in the proximal direction, asseen in FIG. 6B until is fully expands into its radially expandedconfiguration which engages the vessel walls and alleviates the stenosiscaused by the compression, as seen in FIG. 6C. The delivery catheter isthen removed from the patient. In this exemplary method, as well asothers described herein, the delivery catheter may be introducedpercutaneously into the vessel and advanced transluminally over aguidewire, such as an 0.035″ guidewire. Alternatively, the catheter maybe introduced via a surgical cutdown.

FIGS. 7A-7C illustrate another exemplary method of treating a vesselwith the bi-directional stent delivery system such as those previouslydescribed above. In FIG. 7A the delivery catheter is advanced to atarget treatment site in a vessel V. In this embodiment the treatmentsite is a stenotic region S of a vein caused by compression fromsurrounding vessels, bone, or other anatomical structures. The deliverycatheter includes an inner shaft 702, middle shaft 704, outer shaft 706,shuttle sheath 710, proximal lock 708, distal lock 712, and nose cone614. Other aspects of the delivery catheter, such as the proximal hubshave been omitted for clarity. The proximal lock 708 is shown in theunlocked configuration (shown by the white rectangle), while the distallock 712 is shown in the locked configuration (shown by the darkenedrectangle). Once the catheter is advanced to the target treatment site,the inner shaft is advanced distally, thereby also advancing the shuttlesheath 710. The stent 716 becomes unconstrained and self expands in thedistal direction, as seen in FIG. 7B until it fully expands into itsradially expanded configuration which engages the vessel walls andalleviates the stenosis caused by the compression, as illustrated inFIG. 7C. The delivery catheter is then removed from the patient.

FIGS. 8A-8B illustrate exemplary stenting of a vein as a treatment forvenous stenosis. Venous stenosis may be caused by clotting, scarringfollowing blood clots or by focal external compressive forces on avenous vessel (such as in the femoral vein where it crosses the inguinalligament or in the pelvic vein where it is crossed by overlaying pelvicarteries). The stent or stents may be delivered to the vein using any ofthe embodiments described above. FIGS. 8A-8B illustrate a veinexperiencing external compressive forces. In FIG. 8A the right commoniliac artery RCIA is nested against the left common iliac vein LCIV. Thespine SP is posterior to both vessels RCIA, LCIV, therefore the leftcommon iliac vein LCIV may be pinched in between a portion of the rightcommon iliac artery RCIV and the spine SP. FIG. 8B illustrates a crosssection of FIG. 8A and highlights the pinched portion of the left commoniliac vein LCIV. Pinching of the vein obstructs venous outflow. Venousoutflow obstruction of the iliac vein, the common outflow tract of thelower limb, can result in severe clinical symptoms. Obstruction of theiliac veins can be attributed to thrombus formation or from externalcompression from the overlying arterial tree, with possible additionalpressure extending from the spine. Venous outflow obstruction is aclinically relevant contributor to chronic venous disease. When combinedwith venous reflux, outflow obstruction can lead to venous hypertensionand the most severe symptoms associated with advanced venous diseasesuch as swelling, discoloration, claudication and ulceration.

Treatment has traditionally been by surgical bypass. However, in thepast decade, percutaneous endovenous stenting has emerged as the methodof choice in treating venous outflow obstruction due to chronic venousdisease. However, there are currently no FDA approved stents or deliverysystems for this treatment, and therefore such use is considered offlabel use. The placement of stents has also proven useful to relieveobstruction that has been revealed after removal of acute iliofemoralthrombus, after a DVT or from obstruction that has been caused bymalignant tumors or retroperitoneal thrombosis.

Stenting of the vein alleviates the pinch point, thereby permittingnormal venous outflow. One or more stents may be placed in the vein. Incases where multiple stents are deployed, the stents may be placedend-to-end, or the stents may be overlapped with one another. FIG. 9illustrates how two stents 901, 902 may have a region 903 where the twostents overlap with one another. In this embodiment, stent 902 isradially expanded such that a portion of the stent expands into theother stent 901. Overlapping of stents is discussed in greater detail inU.S. patent application Ser. No. 12/903,056, previously incorporated byreference. The stents in this embodiment or those described elsewhere inthis specification may also include a therapeutic agent such as anantithrombogenic such as heparin, a thrombolytic agent, or anothertherapeutic agent for reducing blood clots or for another therapy.

In any of the exemplary methods described herein, after the stent orstents have been deployed in the vessel or target treatment site, theymay be post-dilated using a balloon catheter in order to tack the stentsinto the tissue and maximize their expanded diameter. This may beperformed with a separate balloon dilatation catheter, or a balloon orother expandable member may be included with embodiments of the deliverysystem disclosed herein. Positioning and expansion of stents may beverified using intravascular ultrasound (IVUS). The IVUS catheter may bea separate catheter or it may be integrated into the present deliverysystem. In some embodiments, the IVUS probe is integrated into astandard guidewire, such as an 0.035″ guidewire, therefore aconventional guidewire is replaced by the IVUS guidewire.

Although the exemplary embodiments have been described in some detailfor clarity of understanding and by way of example, a variety ofadditional modifications, adaptations and changes may be clear to thoseof skill in the art. One of skill in the art will appreciate that thevarious features described herein may be combined with one another orsubstituted with one another. Hence, the scope of the present inventionis limited solely by the appended claims.

What is claimed is:
 1. A bi-directional method for deploying aprosthesis at a treatment site in a patient, said method comprising:providing a delivery catheter comprising a prosthesis having a proximalend and a distal end, the prosthesis in a collapsed configuration anddisposed on the delivery catheter, wherein the delivery cathetercomprises an inner elongate shaft, an outer elongate shaft and a shuttlesheath disposed over the prosthesis; delivering the prosthesis to thetarget treatment site; selecting a deployment direction for theprosthesis, wherein the deployment direction comprises radiallyexpanding the prosthesis from the proximal end thereof to the distal endthereof, or radially expanding the prosthesis from the distal endthereof to the proximal end thereof, wherein selecting one deploymentdirection for the prosthesis comprises: coupling the inner elongateshaft with the shuttle sheath; decoupling the outer elongate shaft fromthe shuttle sheath; distally advancing the inner elongate shaft distallythereby advancing the shuttle sheath distally away from the prosthesis;and radially expanding the prosthesis from the proximal end thereof tothe distal end thereof; removing a constraint from the prosthesisthereby permitting the prosthesis to radially expand in the selecteddeployment direction; radially expanding the prosthesis from thecollapsed configuration to an expanded configuration in the selecteddeployment direction so that the expanded prosthesis engages tissue atthe target treatment site; and withdrawing the delivery catheter fromthe patient and leaving the prosthesis deployed at the target treatmentsite.
 2. The method of claim 1, wherein the prosthesis comprises a firststent.
 3. The method of claim 1, wherein the prosthesis comprises afirst stent and a second stent unattached and axially separated from thefirst stent by a gap.
 4. The method of claim 1, wherein delivering theprosthesis comprises advancing the delivery catheter through vasculatureof the patient to the target treatment site.
 5. The method of claim 1,wherein the delivery catheter has a proximal end, a distal end, and alumen therebetween, and delivering the prosthesis comprises slidablyadvancing the delivery catheter over a guidewire disposed in the lumen.6. The method of claim 1, wherein delivering the prosthesis comprisespositioning the prosthesis in a vein.
 7. The method of claim 6, whereinthe vein comprises the iliac vein.
 8. The method of claim 1, whereincoupling the inner elongate shaft with the shuttle sheath comprisesthreadably engaging the inner elongate shaft with the shuttle sheath. 9.The method of claim 1, wherein coupling the inner elongate shaft withthe shuttle sheath comprises helically engaging the inner elongate shaftwith the shuttle sheath.
 10. The method of claim 1, wherein couplingcomprises coupling the inner elongate shaft and the shuttle sheath witha bayonet coupling.
 11. The method of claim 1, wherein decoupling theouter elongate shaft from the shuttle sheath comprise threadablydisengaging the outer elongate shaft from the shuttle sheath.
 12. Themethod of claim 1, wherein decoupling the outer elongate shaft from theshuttle sheath comprise helically disengaging the outer elongate shaftfrom the shuttle sheath.
 13. The method of claim 1, wherein decouplingcomprises releasing a bayonet coupling between the outer elongate shaftand the shuttle sheath.
 14. The method of claim 1, wherein selectinganother deployment direction for the prosthesis comprises: coupling theouter elongate shaft with the shuttle sheath; proximally retracting theouter elongate shaft thereby retracting the shuttle sheath proximallyaway from the prosthesis; and radially expanding the prosthesis from thedistal end thereof to the proximal end thereof.
 15. The method of claim14, wherein coupling the outer elongate shaft with the shuttle sheathcomprises threadably engaging the outer elongate shaft with the shuttlesheath.
 16. The method of claim 14, wherein coupling the outer elongateshaft with the shuttle sheath comprises helically engaging the outerelongate shaft with the shuttle sheath.
 17. The method of claim 14,wherein coupling comprises coupling the outer elongate shaft and theshuttle sheath with a bayonet coupling.
 18. The method of claim 14,wherein selecting another deployment direction further comprises:decoupling the inner elongate shaft from the shuttle sheath.
 19. Themethod of claim 18, wherein decoupling the inner elongate shaft from theshuttle sheath comprises threadably decoupling the inner elongate shaftfrom the shuttle sheath.
 20. The method of claim 18, wherein decouplingthe inner elongate shaft from the shuttle sheath comprises helicallydecoupling the inner elongate shaft from the shuttle sheath.
 21. Themethod of claim 18, wherein decoupling comprises releasing a bayonetcoupling between the inner elongate shaft and the shuttle sheath. 22.The method of claim 14, wherein removing the constraint comprisesproximally retracting the shuttle sheath away from the prosthesis sothat the prosthesis is unconstrained from radial expansion in adirection extending from the distal end of the prosthesis to theproximal end of the prosthesis.
 23. The method of claim 1, whereinremoving the constraint comprises distally advancing the shuttle sheathaway from the prosthesis so that the prosthesis is unconstrained fromradial expansion in a direction extending from the proximal end of theprosthesis to the distal end of the prosthesis.
 24. The method of claim1, wherein radially expanding the prosthesis comprises self-expanding astent.
 25. The method of claim 1, wherein withdrawing the deliverycatheter from the patient comprises withdrawing the delivery catheterfrom the patient's vasculature.
 26. The method of claim 1, wherein theprosthesis comprises two prostheses, and selecting the deploymentdirection for the two prostheses comprises: selecting a first deploymentdirection for the first prosthesis; radially expanding the firstprosthesis in the first deployment direction; and radially expanding thesecond prosthesis in a second deployment direction opposite of the firstdeployment direction.
 27. The method of claim 1, further comprisingvisualizing the expanded prosthesis.
 28. The method of claim 27, whereinvisualizing comprises observing the expanded prosthesis with ultrasoundor fluoroscopy.
 29. The method of claim 27, further comprisingretracting the radially expanded prosthesis into a shuttle sheath;repositioning the prosthesis; and radially expanding the prosthesis. 30.The method of claim 1, further comprising dilating the radially expandedprosthesis with an expandable member.
 31. A method for deploying aprosthesis at a treatment site in a patient, said method comprising:providing a delivery catheter comprising a prosthesis having a proximalend and a distal end, the prosthesis in a collapsed configuration anddisposed on the delivery catheter, and an outer shaft of the deliverycatheter being uncoupled from a shuttle sheath disposed over theprothesis; delivering the prosthesis to the target treatment site;deploying the prosthesis by radially expanding the prosthesis from theproximal end thereof to the distal end thereof by distally advancing aninner shaft to advance distally, the shuttle sheath disposed over theprosthesis, to thereby remove a constraint from the prosthesis and allowthe prosthesis to radially expand from the proximal end to the distalend; and withdrawing the delivery catheter from the patient and leavingthe prosthesis deployed at the target treatment site.